Getting 9.7 to one compression 103BB, '07 touring

[waltcentral]

  Wiseco makes 9.0 or 10.5 to 1.  I believe CP makes only 10.0 to 1 but there online catalog for haley is not updated. KB makes what seems to be the biggest choice and will call them Monday.  Because of reputation I would like to use either the SE flattops or Wiseco but the question is what is most acceptable to get the correct comp, and what will yeild the best long term results.
  I have been told that the SE Cast pistons are good for 100k in resonable builds and since the person doing suggesting this is not trying to sell me pistons (he will do the heads and pistons though) I tend to believe him.
   Is it proper to open up the combustion chamber to 89 or 90 cc to gest the compression right or is it better to start with a 9.o to 1 setup and keep squish at .030 and shave the heads to possibly 80cc? 
Walt

[dave629]

I think you need the The Calculator. This is an .xls file, somewhere on this site and others (like Big Boyz), to assist in deciding what features you need in your build. Hopefully some more experienced guys will chime in to help you out.

[waltcentral]

  I am using the calculator on the Big Boyz sight.  In fact I am considering them for the build as they have no problem getting the deck height right by shaving the bottom of the cylinders.

[DaleW]

I thought I saw CP pistons listed with 9.5:1.

Dale

[waltcentral]

 They said they will not work on '07 and up, I was told rod will hit piston skirt.   

[wolf_59]

According to the bigboyz calculator with .030 gead gasket you need 87.5 cc
Nice calculator go check it out

[waltcentral]

  Wolf,  using the Big Boyz calculator for a 103 and cast SE flatops and 0 deck cylinders and .030 headgasket I am looking at 89 - 90cc combustion chambers.  With Wisecos 9.0 to 1 pistons and untouched deck height (probably pistons down in bore .009) I am looking at 80-82cc chambers.

[Don D]

Flat tops put you at 10/1 with .030 HG, nominally with the actual head volume an unknown variance.
Do not use a dished piston with the concave portion under the flat squish area. Instead if you can't live with 10/1 an accurate opening up of the chamber slightly is easy and will get you exactly where you want to get to. Keep the squish tight and don't be tempted to use a thick HG.

[waltcentral]

  Thanks Dewey,  that is as I suspected but wanted to ckeck before. 

[PanHeadRed]

>Is it proper to open up the combustion chamber to 89 or 90 cc to gest the compression right <

IMO, it's more then proper, if done correctly it's a benifit in many ways.

>is it better to start with a 9.o to 1 setup and keep squish at .030 and shave the heads to possibly 80cc?<

If you cut them that much you limit your options in the future.

 

[Lamar07]

what is the average cc on stock heads?

[Don D]

86cc

[HD/Wrench]

Well CP makes a 95 to 103 piston and then they make 96 to 103 pistons. Compression ht  1.092 for 99-06  and comp ht is 1.083 for 07+ engines. Cp stated that some customers had issues with the oiling jets with the old piston design, so overall this new pistons is just a bit shorted. Ourselves have not had issues with the early or late design.  With a 96 inch engien you will need to check TDC  making sure you are no more than .005 down ( I like to see less than .003) That piston is a 10.1 with a 5.5 cc dome part number M5080. If the customer has a head that is not going to allow us to get to to a lower compression ratio. Reduce the dome on the piston is a quick and easy fix in house.   As for CC in heads we see the large % of them in the 84-87  so 86 is a good starting point. I would use a .030 head gasket with that build.  With 86 cc ( give or take they really need to be cc and balanced if needed) you are 9.8 range with that piston converted to a flat top.

[se]

doing a bagger build down at the shop now it is getting cast pistons customer rides a lot of miles. also this is his second build heads went bad decided to chande the whole top end .Baisley super street heads going on this time with a tw6 hg possibley. butbaisley are a definate.

[Hillside Motorcycle]

No harm whatsoever in increasing chamber volume.